[PATCH 3.12 071/123] MIPS: dma-default: Fix 32-bit fall back to GFP_DMA

From: Jiri Slaby
Date: Wed Oct 28 2015 - 10:15:49 EST

From: James Hogan <james.hogan@xxxxxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.


commit 53960059d56ecef67d4ddd546731623641a3d2d1 upstream.

If there is a DMA zone (usually 24bit = 16MB I believe), but no DMA32
zone, as is the case for some 32-bit kernels, then massage_gfp_flags()
will cause DMA memory allocated for devices with a 32..63-bit
coherent_dma_mask to fall back to using __GFP_DMA, even though there may
only be 32-bits of physical address available anyway.

Correct that case to compare against a mask the size of phys_addr_t
instead of always using a 64-bit mask.

Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
Fixes: a2e715a86c6d ("MIPS: DMA: Fix computation of DMA flags from device's coherent_dma_mask.")
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/9610/
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
arch/mips/mm/dma-default.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index 5f8b95512580..7dd78fc991bf 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -92,7 +92,7 @@ static gfp_t massage_gfp_flags(const struct device *dev, gfp_t gfp)
#if defined(CONFIG_ZONE_DMA) && !defined(CONFIG_ZONE_DMA32)
- if (dev->coherent_dma_mask < DMA_BIT_MASK(64))
+ if (dev->coherent_dma_mask < DMA_BIT_MASK(sizeof(phys_addr_t) * 8))
dma_flag = __GFP_DMA;

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